JP2007115604A - Laminated structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stack structure capable of making small and compact, and capable of uniformly applying a load at all times to a stack member even when using temperature is varied. <P>SOLUTION: In the stack structure 1 equipped with a solid oxide fuel cell 2 which is a plurality of flat stacking members and a fastening pressing member pressing and fastening the solid oxide fuel cell in the stacking direction, and repeating expansion and contraction in the stacking direction by variation of using temperature, and at least a part of the fastening pressing member 4 is used as an expansion contraction part 4A pressing at all times in a using temperature range a plurality of solid oxide fuel cells 2 made of a shape-memory alloy and alternately stacked each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

    The present invention is formed by laminating a plurality of laminated members having a flat plate shape, and a laminated structure that repeats expansion and contraction in the laminating direction according to a change in use temperature, for example, a fuel electrode supplied with fuel gas and an oxidant gas. The present invention relates to a laminated structure formed by laminating a plurality of solid oxide fuel cells each having a polymer electrolyte membrane sandwiched between supplied oxidant electrodes.

Conventionally, as a laminated structure as described above, for example, a laminated body formed by laminating a plurality of solid oxide fuel cells as a laminated member is sandwiched between end plates, and a plurality of pieces penetrating the edge portions of these end plates are used. There is a fuel cell stack structure in which a fastening plate adjacent to one end plate and the other end plate are fastened by screwing nuts into both ends of the stud bolt, and in this fuel cell stack structure, one end The laminated body was pressed from both sides by the elastic force of the disc spring interposed between the plate and the clamping plate to collect current and perform gas sealing.
JP 2002-151135 A

  However, in the fuel cell stack structure as the laminated structure described above, since the disc spring and the clamping plate are used to pressurize the laminated body from both sides, the mass is increased by the amount of these members and the accommodation space is increased. There was a problem of needing.

  In addition, since the disc spring used for pressurization is arranged in the central portion where the stud bolt of the fastening plate is not located, the central portion of the fastening plate is bent, and the solid oxide fuel cell is evenly distributed. There is a problem that a load cannot be applied, and it has been a conventional problem to solve these problems.

  The present invention has been made by paying attention to the above-described conventional problems, and can achieve light weight and downsizing. In addition, even when the use temperature changes, the load is always applied evenly to the laminated member. An object of the present invention is to provide a laminated structure that can be used.

  The present invention includes a laminated member having a plurality of flat plate shapes, and a fastening pressure member that presses and fastens the laminated member in the laminated direction in a state where the laminated members are laminated, and expands and contracts in the laminated direction due to a change in use temperature. In the laminated structure to be repeated, at least a part of the fastening pressure member is configured to be a stretchable part that is formed of a shape memory alloy and laminated to each other and constantly pressurizes in the laminating direction within a range of operating temperatures. The structure of this laminated structure is a means for solving the above-described conventional problems.

  In the laminated structure of the present invention, the fastening pressure member having a stretchable portion made of a shape memory alloy is used to always press and fasten the laminated members laminated in the laminating direction within the operating temperature range. Thus, the mass can be reduced and the space can be saved as much as the disc spring and the clamping plate that are conventionally used to press the laminated member from both sides are not necessary.

  And in the laminated structure of this invention, since the disk spring is not used to pressurize a laminated member from both sides, the part which supports this does not curve, As a result, with respect to a laminated member Thus, the load can always be applied evenly.

  According to the laminated structure of the present invention, since it has the above-described configuration, it is possible to always reduce the size and weight of the laminated member regardless of expansion and contraction due to a change in use temperature of the laminated members laminated to each other. A very good effect is obtained that the load can be applied evenly.

  In the laminated structure of the present invention, the entire fastening pressure member can be formed as an expansion / contraction part made of a shape memory alloy.

  When the above-described configuration is employed, distortion due to tightening occurs in the entire fastening pressure member in accordance with changes in the operating temperature, and a more stable tightening force can be obtained.

  Further, in the laminated structure of the present invention, it is possible to adopt a configuration in which a portion other than the stretchable portion of the fastening pressure member is formed as a non-stretchable portion. The cross-sectional area of the expansion / contraction part of the fastening pressure member can be set smaller than that of the non-expansion / contraction part.

  As described above, when a portion other than the expansion / contraction portion of the fastening pressure member is formed as a non-expansion / contraction portion, strain is selectively concentrated on the expansion / contraction portion made of the shape memory alloy. Therefore, it is only necessary to perform management, and therefore strain management becomes easy.

  And as mentioned above, when the strength of the expansion / contraction part of the fastening pressure member is set lower than that of the non-expansion / contraction part, the expansion / contraction part can be more stably distorted, whereas the fastening pressure member If the cross-sectional area of the expansion / contraction part is set to be smaller than that of the non-expansion / contraction part, the expansion / contraction part can be more stably distorted. Management can be performed.

  Furthermore, in the laminated structure of the present invention, when the operating temperature is −20 to 100 ° C., the strain generated in the expansion and contraction portion of the fastening pressure member can be set to 2 to 6%.

  When the above-described configuration is adopted, a substantially constant tightening force can be obtained by the shape memory function of the shape memory alloy forming the stretchable portion.

  Furthermore, in the laminated structure of the present invention, the fastening pressure member has a plate shape, the fastening pressure member has a rod shape, or the fastening pressure member has a linear shape. It is possible to adopt the structure which has been carried out suitably.

  In this way, when the fastening pressure member has a plate shape, the space can be saved as much as it is not necessary to use a member such as a nut, and the fastening pressure member has a rod shape. If the configuration is used, the tightening operation can be easily performed by using the tightening nut, and further, if the configuration in which the fastening pressure member is formed in a linear shape is adopted, the weight can be further reduced. Will be.

  Furthermore, in the laminated structure of the present invention, the expansion / contraction part of the fastening pressure member can be made of a shape memory alloy having an austenite transformation end temperature of 100 ° C. or higher. Since the shape memory alloy that forms a martensite phase that exhibits a more stable shape memory function, a more stable stress is generated, and a more stable tightening force can be obtained.

  Furthermore, a solid electrolyte fuel cell in which a polymer electrolyte membrane is sandwiched between a fuel electrode to which fuel gas is supplied and an oxidant electrode to which oxidant gas is supplied is used as a laminated member, and the solid electrolyte as the laminated member When a plurality of type fuel cells are stacked and these solid oxide fuel cells stacked on each other are pressed in the stacking direction by the above-described fastening pressure member and fastened, a fuel cell stack structure to which the present invention is applied is obtained. Thus, such a fuel cell stack structure can be reduced in weight and size.

  In other words, since more solid oxide fuel cells can be mounted as compared with the conventional one, the output performance is improved, and therefore, it is suitable for in-vehicle use.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example.

  1 to 3 show an embodiment of the laminated structure of the present invention. In this embodiment, the laminated structure of the present invention is a fuel cell stack structure.

  As shown in FIGS. 1 and 2, the fuel cell stack structure 1 is a solid body in which a polymer electrolyte membrane is sandwiched between a fuel electrode supplied with a fuel gas and an oxidant electrode supplied with an oxidant gas. A plurality of electrolyte fuel cells 2 are provided, and these solid electrolyte fuel cells 2 are stacked and sandwiched between end plates 3 and 3 from both sides. The nuts 5 are screwed into the upper and lower end portions of the fastening pressure members 4 having four rod shapes, whereby the solid oxide fuel cells 2 stacked on each other are pressed and fastened in the stacking direction.

  In this case, the intermediate portion of the rod-shaped tightening additional pressure member 4 is formed as a stretchable portion 4A made of a shape memory alloy, and both end portions are formed as non-stretchable portions 4B. By so doing, the solid oxide fuel cell 2 can be pressurized in the stacking direction.

  The above shape memory alloy has a martensitic phase at a temperature equal to or lower than the austenite transformation finish temperature, and there is a region that does not undergo plastic deformation (permanent deformation) due to twin deformation. In the case of the shape memory alloy (Ni-Ti alloy with 49.5 at% Ni) used in this example, the stress-strain diagram of FIG. 3A (the Ni-Ti alloy was subjected to shape memory treatment at 400 ° C. As shown in the stress-strain diagram at room temperature (about 25 ° C.), there is a strain range in which the stress does not change greatly even when about 6% strain is applied by twin deformation. In the strain range of%, the stress is almost constant at 330 MPa.

  At this time, assuming that the natural length of the expansion / contraction part 4A is 75 mm, even if there is a change of about 3 mm from 1.5 to 4.5 mm, it is possible to output a substantially constant stress. Even if there is an error of about 4 mm in each screw amount of the nut 5 screwed into the pressure member 4, the solid oxide fuel cell 2 can be pressed and tightened in the stacking direction with a substantially constant tightening force.

  In the fuel cell stack structure 1 of this example, the use temperature range is −20 to 100 ° C., and when the use temperature changes, the expansion and contraction are repeated in the stacking direction, and the stacking direction dimension L is 360 mm. It expands and contracts in the range of 1.5 to 3 mm.

  As described above, the shape memory alloy employed in the expansion / contraction part 4A of the fastening pressure member 4 in this example is a Ni-Ti alloy having a Ni content of 49.5 at%, and the austenite transformation end temperature is 100 ° C or higher. It is supposed to be.

  Therefore, in this embodiment, the tightening additional pressure member 4 was set so that a strain of about 2% was generated in the stretchable portion 4A at -20 ° C. That is, at −20 ° C., the solid oxide fuel cell 2 was pressed and tightened in the stacking direction with a tightening force of about 330 MPa.

  The temperature of the fuel cell stack structure 1 increases as it is used. Along with this, a temperature is applied to the expansion / contraction part 4A of the fastening pressure member 4, and by this temperature, a shape recovery force is generated in the expansion / contraction part 4A to return to the natural length. As a result, the fastening pressure member 4 always pressurizes the solid oxide fuel cell 2 in the stacking direction by the shape recovery force generated in the expansion / contraction part 4A.

  Moreover, although the said fuel cell stack structure 1 may rise to a maximum of 100 degreeC, since the use temperature range is a martensite, it can be used by more stable recovery stress.

  Here, even if the austenite transformation end temperature of the shape memory alloy is less than 100 ° C., there is a range of austenite within the operating temperature range. Even in this austenite state, the stretchable portion 4A has a shape memory alloy. The shape recovery stress that tries to return to the natural length is generated by the pseudo-elastic function.

  As shown in the stress-strain diagram in the austenite phase of FIG. 3 (b), the stress of the biphasic deformation is higher than that of the martensite phase, but the pseudoelastic effect appears to return to the initial shape. If the pseudoelastic force for returning to the natural length is utilized as the tightening force, the solid oxide fuel cell 2 can always be pressurized in the stacking direction.

  Furthermore, in this embodiment, the fastening pressure member is formed by setting the strength of the Ni-Ti alloy forming the stretchable portion 4A of the fastening pressure member 4 to be lower than the yield strength at which the non-stretchable portion 4B is plastically deformed. When the nut 5 is screwed into the nut 4, the stretchable portion 4A is distorted more intensively. Therefore, the strain can be easily managed because the size of the stretchable portion 4A can be managed. That is, the tightening force can be easily managed.

  In the fuel cell stack structure 1 described above, the solid electrolyte fuel cells 2 stacked in a plurality of layers are always pressed in the stacking direction within the operating temperature range by the fastening pressure member 4 having the expansion / contraction part 4A made of a shape memory alloy. Since the fastening is performed, the mass can be reduced and the space can be saved to the extent that the disc spring and the fastening plate that are conventionally used to pressurize the laminated member from both sides are not necessary.

  As described above, in the fuel cell stack structure 1 described above, since the solid oxide fuel cell 2 can be mounted in a larger amount by omitting the disc spring and the clamping plate, the output performance is improved. It will be suitable for in-vehicle use.

  In the fuel cell stack structure 1 described above, since the fastening pressure member 4 has a rod shape, the fastening operation is facilitated by using the fastening nut 5.

  FIG. 4 shows another embodiment of the laminated structure of the present invention. This embodiment also shows the case where the laminated structure of the present invention is a fuel cell stack structure. As shown in FIG. 4, the fuel cell stack structure 11 of this embodiment is the same as that of the previous embodiment. The difference from the fuel cell stack structure 1 is that the cross-sectional area of the expansion / contraction part 14A of the fastening pressure member 14 is set smaller than that of the non-expansion / contraction part 14B, and the other configuration is the fuel cell stack in the previous embodiment. It is the same as the structure 1.

  In this fuel cell stack structure 11, since the cross-sectional area of the expansion / contraction part 14A of the fastening pressure member 14 is set smaller than that of the non-expansion / contraction part 14B, the expansion / contraction part 14A can be strained more stably. In addition, the tightening force can be managed by managing the cross-sectional area of the stretchable portion 14A.

  FIG. 5 shows still another embodiment of the laminated structure of the present invention. This embodiment also shows the case where the laminated structure of the present invention is a fuel cell stack structure. As shown in FIG. 5, the fuel cell stack structure 21 of this embodiment is the same as that of the previous embodiment. The fuel cell stack structure 11 is different from the fuel cell stack structure 11 in that a fastening pressure member 24 having an expansion / contraction portion 24A made of a shape memory alloy is provided between the fastening pressure members 14 and 14 disposed at both ends of the end plates 3 and 3 in the drawing. And the cross-sectional areas of the stretchable part 24A and the non-stretchable part 24B of the fastening pressure member 24 are both set larger than the stretchable part 14A and the non-stretchable part 14B of the fastening pressure member 14, The configuration is the same as that of the fuel cell stack structure 11 in the previous embodiment.

  In this fuel cell stack structure 21, since the cross-sectional area of the expansion / contraction part 24A of the fastening pressure member 24 arranged at the center is set larger than the expansion / contraction part 14 of the fastening pressure member 14 arranged on both sides, The tightening force increases. Therefore, a large tightening force can be applied to the central portions of the end plates 3 and 3 where it is difficult to apply the tightening pressure, and the solid oxide fuel cell 2 can be more uniformly tightened and pressurized.

  6 and 7 show still another embodiment of the laminated structure of the present invention. Also in this embodiment, the case where the laminated structure of the present invention is a fuel cell stack structure is shown. As shown in FIGS. 6 and 7, the fuel cell stack structure 31 of this embodiment includes an intermediate portion. Is formed as a stretchable portion 34A made of a shape memory alloy and has a plate-like fastening pressure member 34 having both end portions formed as a non-stretchable portion 34B. The upper and lower ends of the fastening pressure member 34 are connected via bolts 36. By fixing to the end plates 3 and 3, the solid oxide fuel cells 2 stacked on each other are pressed and tightened in the stacking direction.

  In the fuel cell stack structure 31, the fastening pressure member 34 has a plate shape, so that the space can be saved as much as it is not necessary to use a member such as a nut.

  8 and 9 show still another embodiment of the laminated structure of the present invention. Also in this embodiment, the case where the laminated structure of the present invention is a fuel cell stack structure is shown. As shown in FIGS. 8 and 9, the fuel cell stack structure 41 of this embodiment is entirely composed. A linear fastening pressure member 44 made of a shape memory alloy is provided, and both ends of the fastening pressure member 44 are fixed to one end plate 3 via bolts 46, and an intermediate portion of the fastening pressure member 44 is provided. By alternately hooking on hooks 47 provided on the end plates 3, 3, the solid oxide fuel cells 2 stacked on each other are pressed in the stacking direction and fastened.

  In the fuel cell stack structure 31, the fastening pressure member 44 has a linear shape, so that space can be saved as much as it is not necessary to use a member such as a nut, and the weight can be further reduced. Will be.

  When the fastening pressure member 44 has a linear shape, the fastening pressure member 44 may be wound around the solid oxide fuel cell 2 stacked on each other. Further weight reduction will be achieved.

  In each of the above-described embodiments, the case where the laminated structure of the present invention is a fuel cell stack structure has been shown. However, the present invention is not limited to this, and the expansion and contraction are repeated in the stacking direction according to the change in use temperature. Any laminated structure can be applied.

It is front explanatory drawing of the fuel cell stack structure which shows one Example of the laminated structure of this invention. Example 1 It is side surface explanatory drawing of the fuel cell stack structure of FIG. Example 1 FIG. 2 is a stress-strain diagram (a) of the martensite phase and a stress-strain diagram (b) of the austenite phase of the shape memory alloy used for the tightening pressure member in the fuel cell stack structure of FIG. 1. It is front explanatory drawing of the fuel cell stack structure which shows the other Example of the laminated structure of this invention. (Example 2) It is front explanatory drawing of the fuel cell stack structure which shows other Example of the laminated structure of this invention. (Example 3) It is front explanatory drawing of the fuel cell stack structure which shows other Example of the laminated structure of this invention. (Example 4) It is side surface explanatory drawing of the fuel cell stack structure of FIG. (Example 4) It is front explanatory drawing of the fuel cell stack structure which shows other Example of the laminated structure of this invention. (Example 5) It is side surface explanatory drawing of the fuel cell stack structure of FIG. (Example 5)

Explanation of symbols

1,11,21,31,41 Fuel cell stack structure (laminated structure)
2 Solid oxide fuel cell 4, 14, 24, 34, 44 Fastening pressure member 4A, 14A, 24A, 34A Stretchable part 4B, 14B, 24B, 34B Non-stretchable part

Claims (11)

  A laminated structure having a plurality of flat plate-like laminated members and a fastening pressure member that presses and fastens the laminated members in the laminated direction in a state in which these laminated members are laminated, and repeatedly expands and contracts in the laminated direction according to a change in use temperature. A laminate structure characterized in that at least a part of the fastening pressure member is a stretchable part that constantly pressurizes a plurality of laminated members that are made of shape memory alloy and are laminated to each other in a range of operating temperature.   The laminated structure according to claim 1, wherein the whole fastening pressure member is formed as a stretchable part made of a shape memory alloy.   The laminated structure according to claim 1, wherein a portion other than the stretchable portion of the fastening pressure member is formed as a non-stretchable portion.   The laminated structure according to claim 3, wherein the strength of the stretchable portion of the fastening pressure member is set lower than that of the non-stretchable portion.   The laminated structure according to claim 3 or 4, wherein the cross-sectional area of the stretchable portion of the fastening pressure member is set smaller than that of the non-stretchable portion.   The laminated structure according to any one of claims 3 to 5, wherein when the operating temperature is -20 to 100 ° C, the strain generated in the stretchable portion of the fastening pressure member is set to 2 to 6%.   The laminated structure according to any one of claims 1 to 6, wherein the fastening pressure member has a plate shape.   The laminated structure according to any one of claims 1 to 6, wherein the fastening pressure member has a rod shape.   The laminated structure according to any one of claims 1 to 6, wherein the fastening pressure member has a linear shape.   The laminated structure according to any one of claims 1 to 9, wherein the expansion / contraction portion of the fastening pressure member is made of a shape memory alloy having an austenite transformation end temperature of 100 ° C or higher.   A solid electrolyte fuel cell in which a polymer electrolyte membrane is sandwiched between a fuel electrode to which a fuel gas is supplied and an oxidant electrode to which an oxidant gas is supplied is a laminated member, and the solid oxide fuel cell as the laminated member The laminated structure according to any one of claims 1 to 10, wherein a plurality of layers are stacked and pressed by a fastening pressure member in a stacking direction.

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